/*
 * hostapd / EAP-SIM database/authenticator gateway
 * Copyright (c) 2005-2007, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 *
 * This is an example implementation of the EAP-SIM/AKA database/authentication
 * gateway interface that is using an external program as an SS7 gateway to
 * GSM/UMTS authentication center (HLR/AuC). hlr_auc_gw is an example
 * implementation of such a gateway program. This eap_sim_db.c takes care of
 * EAP-SIM/AKA pseudonyms and re-auth identities. It can be used with different
 * gateway implementations for HLR/AuC access. Alternatively, it can also be
 * completely replaced if the in-memory database of pseudonyms/re-auth
 * identities is not suitable for some cases.
 */

#include "includes.h"
#include <sys/un.h>

#include "common.h"
#include "eap_common/eap_sim_common.h"
#include "eap_server/eap_sim_db.h"
#include "eloop.h"

struct eap_sim_pseudonym {
        struct eap_sim_pseudonym *next;
        u8 *identity;
        size_t identity_len;
        char *pseudonym;
};

struct eap_sim_db_pending {
        struct eap_sim_db_pending *next;
        u8 imsi[20];
        size_t imsi_len;
        enum { PENDING, SUCCESS, FAILURE } state;
        void *cb_session_ctx;
        struct os_time timestamp;
        int aka;
        union {
                struct {
                        u8 kc[EAP_SIM_MAX_CHAL][EAP_SIM_KC_LEN];
                        u8 sres[EAP_SIM_MAX_CHAL][EAP_SIM_SRES_LEN];
                        u8 rand[EAP_SIM_MAX_CHAL][GSM_RAND_LEN];
                        int num_chal;
                } sim;
                struct {
                        u8 rand[EAP_AKA_RAND_LEN];
                        u8 autn[EAP_AKA_AUTN_LEN];
                        u8 ik[EAP_AKA_IK_LEN];
                        u8 ck[EAP_AKA_CK_LEN];
                        u8 res[EAP_AKA_RES_MAX_LEN];
                        size_t res_len;
                } aka;
        } u;
};

struct eap_sim_db_data {
        int sock;
        char *fname;
        char *local_sock;
        void (*get_complete_cb)(void *ctx, void *session_ctx);
        void *ctx;
        struct eap_sim_pseudonym *pseudonyms;
        struct eap_sim_reauth *reauths;
        struct eap_sim_db_pending *pending;
};


static struct eap_sim_db_pending *
eap_sim_db_get_pending(struct eap_sim_db_data *data, const u8 *imsi,
                       size_t imsi_len, int aka)
{
        struct eap_sim_db_pending *entry, *prev = NULL;

        entry = data->pending;
        while (entry) {
                if (entry->aka == aka && entry->imsi_len == imsi_len &&
                    os_memcmp(entry->imsi, imsi, imsi_len) == 0) {
                        if (prev)
                                prev->next = entry->next;
                        else
                                data->pending = entry->next;
                        break;
                }
                prev = entry;
                entry = entry->next;
        }
        return entry;
}


static void eap_sim_db_add_pending(struct eap_sim_db_data *data,
                                   struct eap_sim_db_pending *entry)
{
        entry->next = data->pending;
        data->pending = entry;
}


static void eap_sim_db_sim_resp_auth(struct eap_sim_db_data *data,
                                     const char *imsi, char *buf)
{
        char *start, *end, *pos;
        struct eap_sim_db_pending *entry;
        int num_chal;

        /*
         * SIM-RESP-AUTH <IMSI> Kc(i):SRES(i):RAND(i) ...
         * SIM-RESP-AUTH <IMSI> FAILURE
         * (IMSI = ASCII string, Kc/SRES/RAND = hex string)
         */

        entry = eap_sim_db_get_pending(data, (u8 *) imsi, os_strlen(imsi), 0);
        if (entry == NULL) {
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: No pending entry for the "
                           "received message found");
                return;
        }

        start = buf;
        if (os_strncmp(start, "FAILURE", 7) == 0) {
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: External server reported "
                           "failure");
                entry->state = FAILURE;
                eap_sim_db_add_pending(data, entry);
                data->get_complete_cb(data->ctx, entry->cb_session_ctx);
                return;
        }

        num_chal = 0;
        while (num_chal < EAP_SIM_MAX_CHAL) {
                end = os_strchr(start, ' ');
                if (end)
                        *end = '\0';

                pos = os_strchr(start, ':');
                if (pos == NULL)
                        goto parse_fail;
                *pos = '\0';
                if (hexstr2bin(start, entry->u.sim.kc[num_chal],
                               EAP_SIM_KC_LEN))
                        goto parse_fail;

                start = pos + 1;
                pos = os_strchr(start, ':');
                if (pos == NULL)
                        goto parse_fail;
                *pos = '\0';
                if (hexstr2bin(start, entry->u.sim.sres[num_chal],
                               EAP_SIM_SRES_LEN))
                        goto parse_fail;

                start = pos + 1;
                if (hexstr2bin(start, entry->u.sim.rand[num_chal],
                               GSM_RAND_LEN))
                        goto parse_fail;

                num_chal++;
                if (end == NULL)
                        break;
                else
                        start = end + 1;
        }
        entry->u.sim.num_chal = num_chal;

        entry->state = SUCCESS;
        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Authentication data parsed "
                   "successfully - callback");
        eap_sim_db_add_pending(data, entry);
        data->get_complete_cb(data->ctx, entry->cb_session_ctx);
        return;

parse_fail:
        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Failed to parse response string");
        os_free(entry);
}


static void eap_sim_db_aka_resp_auth(struct eap_sim_db_data *data,
                                     const char *imsi, char *buf)
{
        char *start, *end;
        struct eap_sim_db_pending *entry;

        /*
         * AKA-RESP-AUTH <IMSI> <RAND> <AUTN> <IK> <CK> <RES>
         * AKA-RESP-AUTH <IMSI> FAILURE
         * (IMSI = ASCII string, RAND/AUTN/IK/CK/RES = hex string)
         */

        entry = eap_sim_db_get_pending(data, (u8 *) imsi, os_strlen(imsi), 1);
        if (entry == NULL) {
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: No pending entry for the "
                           "received message found");
                return;
        }

        start = buf;
        if (os_strncmp(start, "FAILURE", 7) == 0) {
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: External server reported "
                           "failure");
                entry->state = FAILURE;
                eap_sim_db_add_pending(data, entry);
                data->get_complete_cb(data->ctx, entry->cb_session_ctx);
                return;
        }

        end = os_strchr(start, ' ');
        if (end == NULL)
                goto parse_fail;
        *end = '\0';
        if (hexstr2bin(start, entry->u.aka.rand, EAP_AKA_RAND_LEN))
                goto parse_fail;

        start = end + 1;
        end = os_strchr(start, ' ');
        if (end == NULL)
                goto parse_fail;
        *end = '\0';
        if (hexstr2bin(start, entry->u.aka.autn, EAP_AKA_AUTN_LEN))
                goto parse_fail;

        start = end + 1;
        end = os_strchr(start, ' ');
        if (end == NULL)
                goto parse_fail;
        *end = '\0';
        if (hexstr2bin(start, entry->u.aka.ik, EAP_AKA_IK_LEN))
                goto parse_fail;

        start = end + 1;
        end = os_strchr(start, ' ');
        if (end == NULL)
                goto parse_fail;
        *end = '\0';
        if (hexstr2bin(start, entry->u.aka.ck, EAP_AKA_CK_LEN))
                goto parse_fail;

        start = end + 1;
        end = os_strchr(start, ' ');
        if (end)
                *end = '\0';
        else {
                end = start;
                while (*end)
                        end++;
        }
        entry->u.aka.res_len = (end - start) / 2;
        if (entry->u.aka.res_len > EAP_AKA_RES_MAX_LEN) {
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: Too long RES");
                entry->u.aka.res_len = 0;
                goto parse_fail;
        }
        if (hexstr2bin(start, entry->u.aka.res, entry->u.aka.res_len))
                goto parse_fail;

        entry->state = SUCCESS;
        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Authentication data parsed "
                   "successfully - callback");
        eap_sim_db_add_pending(data, entry);
        data->get_complete_cb(data->ctx, entry->cb_session_ctx);
        return;

parse_fail:
        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Failed to parse response string");
        os_free(entry);
}


static void eap_sim_db_receive(int sock, void *eloop_ctx, void *sock_ctx)
{
        struct eap_sim_db_data *data = eloop_ctx;
        char buf[1000], *pos, *cmd, *imsi;
        int res;

        res = recv(sock, buf, sizeof(buf), 0);
        if (res < 0)
                return;
        wpa_hexdump_ascii_key(MSG_MSGDUMP, "EAP-SIM DB: Received from an "
                              "external source", (u8 *) buf, res);
        if (res == 0)
                return;
        if (res >= (int) sizeof(buf))
                res = sizeof(buf) - 1;
        buf[res] = '\0';

        if (data->get_complete_cb == NULL) {
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: No get_complete_cb "
                           "registered");
                return;
        }

        /* <cmd> <IMSI> ... */

        cmd = buf;
        pos = os_strchr(cmd, ' ');
        if (pos == NULL)
                goto parse_fail;
        *pos = '\0';
        imsi = pos + 1;
        pos = os_strchr(imsi, ' ');
        if (pos == NULL)
                goto parse_fail;
        *pos = '\0';
        wpa_printf(MSG_DEBUG, "EAP-SIM DB: External response=%s for IMSI %s",
                   cmd, imsi);

        if (os_strcmp(cmd, "SIM-RESP-AUTH") == 0)
                eap_sim_db_sim_resp_auth(data, imsi, pos + 1);
        else if (os_strcmp(cmd, "AKA-RESP-AUTH") == 0)
                eap_sim_db_aka_resp_auth(data, imsi, pos + 1);
        else
                wpa_printf(MSG_INFO, "EAP-SIM DB: Unknown external response "
                           "'%s'", cmd);
        return;

parse_fail:
        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Failed to parse response string");
}


static int eap_sim_db_open_socket(struct eap_sim_db_data *data)
{
        struct sockaddr_un addr;
        static int counter = 0;

        if (os_strncmp(data->fname, "unix:", 5) != 0)
                return -1;

        data->sock = socket(PF_UNIX, SOCK_DGRAM, 0);
        if (data->sock < 0) {
                perror("socket(eap_sim_db)");
                return -1;
        }

        os_memset(&addr, 0, sizeof(addr));
        addr.sun_family = AF_UNIX;
        os_snprintf(addr.sun_path, sizeof(addr.sun_path),
                    "/tmp/eap_sim_db_%d-%d", getpid(), counter++);
        data->local_sock = os_strdup(addr.sun_path);
        if (bind(data->sock, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
                perror("bind(eap_sim_db)");
                close(data->sock);
                data->sock = -1;
                return -1;
        }

        os_memset(&addr, 0, sizeof(addr));
        addr.sun_family = AF_UNIX;
        os_strlcpy(addr.sun_path, data->fname + 5, sizeof(addr.sun_path));
        if (connect(data->sock, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
                perror("connect(eap_sim_db)");
                wpa_hexdump_ascii(MSG_INFO, "HLR/AuC GW socket",
                                  (u8 *) addr.sun_path,
                                  os_strlen(addr.sun_path));
                close(data->sock);
                data->sock = -1;
                return -1;
        }

        eloop_register_read_sock(data->sock, eap_sim_db_receive, data, NULL);

        return 0;
}


static void eap_sim_db_close_socket(struct eap_sim_db_data *data)
{
        if (data->sock >= 0) {
                eloop_unregister_read_sock(data->sock);
                close(data->sock);
                data->sock = -1;
        }
        if (data->local_sock) {
                unlink(data->local_sock);
                os_free(data->local_sock);
                data->local_sock = NULL;
        }
}


/**
 * eap_sim_db_init - Initialize EAP-SIM DB / authentication gateway interface
 * @config: Configuration data (e.g., file name)
 * @get_complete_cb: Callback function for reporting availability of triplets
 * @ctx: Context pointer for get_complete_cb
 * Returns: Pointer to a private data structure or %NULL on failure
 */
void * eap_sim_db_init(const char *config,
                       void (*get_complete_cb)(void *ctx, void *session_ctx),
                       void *ctx)
{
        struct eap_sim_db_data *data;

        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;

        data->sock = -1;
        data->get_complete_cb = get_complete_cb;
        data->ctx = ctx;
        data->fname = os_strdup(config);
        if (data->fname == NULL)
                goto fail;

        if (os_strncmp(data->fname, "unix:", 5) == 0) {
                if (eap_sim_db_open_socket(data))
                        goto fail;
        }

        return data;

fail:
        eap_sim_db_close_socket(data);
        os_free(data->fname);
        os_free(data);
        return NULL;
}


static void eap_sim_db_free_pseudonym(struct eap_sim_pseudonym *p)
{
        os_free(p->identity);
        os_free(p->pseudonym);
        os_free(p);
}


static void eap_sim_db_free_reauth(struct eap_sim_reauth *r)
{
        os_free(r->identity);
        os_free(r->reauth_id);
        os_free(r);
}


/**
 * eap_sim_db_deinit - Deinitialize EAP-SIM DB/authentication gw interface
 * @priv: Private data pointer from eap_sim_db_init()
 */
void eap_sim_db_deinit(void *priv)
{
        struct eap_sim_db_data *data = priv;
        struct eap_sim_pseudonym *p, *prev;
        struct eap_sim_reauth *r, *prevr;
        struct eap_sim_db_pending *pending, *prev_pending;

        eap_sim_db_close_socket(data);
        os_free(data->fname);

        p = data->pseudonyms;
        while (p) {
                prev = p;
                p = p->next;
                eap_sim_db_free_pseudonym(prev);
        }

        r = data->reauths;
        while (r) {
                prevr = r;
                r = r->next;
                eap_sim_db_free_reauth(prevr);
        }

        pending = data->pending;
        while (pending) {
                prev_pending = pending;
                pending = pending->next;
                os_free(prev_pending);
        }

        os_free(data);
}


static int eap_sim_db_send(struct eap_sim_db_data *data, const char *msg,
                           size_t len)
{
        int _errno = 0;

        if (send(data->sock, msg, len, 0) < 0) {
                _errno = errno;
                perror("send[EAP-SIM DB UNIX]");
        }

        if (_errno == ENOTCONN || _errno == EDESTADDRREQ || _errno == EINVAL ||
            _errno == ECONNREFUSED) {
                /* Try to reconnect */
                eap_sim_db_close_socket(data);
                if (eap_sim_db_open_socket(data) < 0)
                        return -1;
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: Reconnected to the "
                           "external server");
                if (send(data->sock, msg, len, 0) < 0) {
                        perror("send[EAP-SIM DB UNIX]");
                        return -1;
                }
        }

        return 0;
}


static void eap_sim_db_expire_pending(struct eap_sim_db_data *data)
{
        /* TODO: add limit for maximum length for pending list; remove latest
         * (i.e., last) entry from the list if the limit is reached; could also
         * use timeout to expire pending entries */
}


/**
 * eap_sim_db_get_gsm_triplets - Get GSM triplets
 * @priv: Private data pointer from eap_sim_db_init()
 * @identity: User name identity
 * @identity_len: Length of identity in bytes
 * @max_chal: Maximum number of triplets
 * @_rand: Buffer for RAND values
 * @kc: Buffer for Kc values
 * @sres: Buffer for SRES values
 * @cb_session_ctx: Session callback context for get_complete_cb()
 * Returns: Number of triplets received (has to be less than or equal to
 * max_chal), -1 (EAP_SIM_DB_FAILURE) on error (e.g., user not found), or
 * -2 (EAP_SIM_DB_PENDING) if results are not yet available. In this case, the
 * callback function registered with eap_sim_db_init() will be called once the
 * results become available.
 *
 * In most cases, the user name is '1' | IMSI, i.e., 1 followed by the IMSI in
 * ASCII format.
 *
 * When using an external server for GSM triplets, this function can always
 * start a request and return EAP_SIM_DB_PENDING immediately if authentication
 * triplets are not available. Once the triplets are received, callback
 * function registered with eap_sim_db_init() is called to notify EAP state
 * machine to reprocess the message. This eap_sim_db_get_gsm_triplets()
 * function will then be called again and the newly received triplets will then
 * be given to the caller.
 */
int eap_sim_db_get_gsm_triplets(void *priv, const u8 *identity,
                                size_t identity_len, int max_chal,
                                u8 *_rand, u8 *kc, u8 *sres,
                                void *cb_session_ctx)
{
        struct eap_sim_db_data *data = priv;
        struct eap_sim_db_pending *entry;
        int len, ret;
        size_t i;
        char msg[40];

        if (identity_len < 2 || identity[0] != EAP_SIM_PERMANENT_PREFIX) {
                wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: unexpected identity",
                                  identity, identity_len);
                return EAP_SIM_DB_FAILURE;
        }
        identity++;
        identity_len--;
        for (i = 0; i < identity_len; i++) {
                if (identity[i] == '@') {
                        identity_len = i;
                        break;
                }
        }
        if (identity_len + 1 > sizeof(entry->imsi)) {
                wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: unexpected identity",
                                  identity, identity_len);
                return EAP_SIM_DB_FAILURE;
        }
        wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: Get GSM triplets for IMSI",
                          identity, identity_len);

        entry = eap_sim_db_get_pending(data, identity, identity_len, 0);
        if (entry) {
                int num_chal;
                if (entry->state == FAILURE) {
                        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Pending entry -> "
                                   "failure");
                        os_free(entry);
                        return EAP_SIM_DB_FAILURE;
                }

                if (entry->state == PENDING) {
                        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Pending entry -> "
                                   "still pending");
                        eap_sim_db_add_pending(data, entry);
                        return EAP_SIM_DB_PENDING;
                }

                wpa_printf(MSG_DEBUG, "EAP-SIM DB: Pending entry -> "
                           "%d challenges", entry->u.sim.num_chal);
                num_chal = entry->u.sim.num_chal;
                if (num_chal > max_chal)
                        num_chal = max_chal;
                os_memcpy(_rand, entry->u.sim.rand, num_chal * GSM_RAND_LEN);
                os_memcpy(sres, entry->u.sim.sres,
                          num_chal * EAP_SIM_SRES_LEN);
                os_memcpy(kc, entry->u.sim.kc, num_chal * EAP_SIM_KC_LEN);
                os_free(entry);
                return num_chal;
        }

        if (data->sock < 0) {
                if (eap_sim_db_open_socket(data) < 0)
                        return EAP_SIM_DB_FAILURE;
        }

        len = os_snprintf(msg, sizeof(msg), "SIM-REQ-AUTH ");
        if (len < 0 || len + identity_len >= sizeof(msg))
                return EAP_SIM_DB_FAILURE;
        os_memcpy(msg + len, identity, identity_len);
        len += identity_len;
        ret = os_snprintf(msg + len, sizeof(msg) - len, " %d", max_chal);
        if (ret < 0 || (size_t) ret >= sizeof(msg) - len)
                return EAP_SIM_DB_FAILURE;
        len += ret;

        wpa_hexdump(MSG_DEBUG, "EAP-SIM DB: requesting SIM authentication "
                    "data for IMSI", identity, identity_len);
        if (eap_sim_db_send(data, msg, len) < 0)
                return EAP_SIM_DB_FAILURE;

        entry = os_zalloc(sizeof(*entry));
        if (entry == NULL)
                return EAP_SIM_DB_FAILURE;

        os_get_time(&entry->timestamp);
        os_memcpy(entry->imsi, identity, identity_len);
        entry->imsi_len = identity_len;
        entry->cb_session_ctx = cb_session_ctx;
        entry->state = PENDING;
        eap_sim_db_add_pending(data, entry);
        eap_sim_db_expire_pending(data);

        return EAP_SIM_DB_PENDING;
}


static struct eap_sim_pseudonym *
eap_sim_db_get_pseudonym(struct eap_sim_db_data *data, const u8 *identity,
                         size_t identity_len)
{
        char *pseudonym;
        size_t len;
        struct eap_sim_pseudonym *p;

        if (identity_len == 0 ||
            (identity[0] != EAP_SIM_PSEUDONYM_PREFIX &&
             identity[0] != EAP_AKA_PSEUDONYM_PREFIX))
                return NULL;

        /* Remove possible realm from identity */
        len = 0;
        while (len < identity_len) {
                if (identity[len] == '@')
                        break;
                len++;
        }

        pseudonym = os_malloc(len + 1);
        if (pseudonym == NULL)
                return NULL;
        os_memcpy(pseudonym, identity, len);
        pseudonym[len] = '\0';

        p = data->pseudonyms;
        while (p) {
                if (os_strcmp(p->pseudonym, pseudonym) == 0)
                        break;
                p = p->next;
        }

        os_free(pseudonym);

        return p;
}


static struct eap_sim_pseudonym *
eap_sim_db_get_pseudonym_id(struct eap_sim_db_data *data, const u8 *identity,
                            size_t identity_len)
{
        struct eap_sim_pseudonym *p;

        if (identity_len == 0 ||
            (identity[0] != EAP_SIM_PERMANENT_PREFIX &&
             identity[0] != EAP_AKA_PERMANENT_PREFIX))
                return NULL;

        p = data->pseudonyms;
        while (p) {
                if (identity_len == p->identity_len &&
                    os_memcmp(p->identity, identity, identity_len) == 0)
                        break;
                p = p->next;
        }

        return p;
}


static struct eap_sim_reauth *
eap_sim_db_get_reauth(struct eap_sim_db_data *data, const u8 *identity,
                      size_t identity_len)
{
        char *reauth_id;
        size_t len;
        struct eap_sim_reauth *r;

        if (identity_len == 0 ||
            (identity[0] != EAP_SIM_REAUTH_ID_PREFIX &&
             identity[0] != EAP_AKA_REAUTH_ID_PREFIX))
                return NULL;

        /* Remove possible realm from identity */
        len = 0;
        while (len < identity_len) {
                if (identity[len] == '@')
                        break;
                len++;
        }

        reauth_id = os_malloc(len + 1);
        if (reauth_id == NULL)
                return NULL;
        os_memcpy(reauth_id, identity, len);
        reauth_id[len] = '\0';

        r = data->reauths;
        while (r) {
                if (os_strcmp(r->reauth_id, reauth_id) == 0)
                        break;
                r = r->next;
        }

        os_free(reauth_id);

        return r;
}


static struct eap_sim_reauth *
eap_sim_db_get_reauth_id(struct eap_sim_db_data *data, const u8 *identity,
                         size_t identity_len)
{
        struct eap_sim_pseudonym *p;
        struct eap_sim_reauth *r;

        if (identity_len == 0)
                return NULL;

        p = eap_sim_db_get_pseudonym(data, identity, identity_len);
        if (p == NULL)
                p = eap_sim_db_get_pseudonym_id(data, identity, identity_len);
        if (p) {
                identity = p->identity;
                identity_len = p->identity_len;
        }

        r = data->reauths;
        while (r) {
                if (identity_len == r->identity_len &&
                    os_memcmp(r->identity, identity, identity_len) == 0)
                        break;
                r = r->next;
        }

        return r;
}


/**
 * eap_sim_db_identity_known - Verify whether the given identity is known
 * @priv: Private data pointer from eap_sim_db_init()
 * @identity: User name identity
 * @identity_len: Length of identity in bytes 
 * Returns: 0 if the user is found or -1 on failure
 *
 * In most cases, the user name is ['0','1'] | IMSI, i.e., 1 followed by the
 * IMSI in ASCII format, ['2','3'] | pseudonym, or ['4','5'] | reauth_id.
 */
int eap_sim_db_identity_known(void *priv, const u8 *identity,
                              size_t identity_len)
{
        struct eap_sim_db_data *data = priv;

        if (identity == NULL || identity_len < 2)
                return -1;

        if (identity[0] == EAP_SIM_PSEUDONYM_PREFIX ||
            identity[0] == EAP_AKA_PSEUDONYM_PREFIX) {
                struct eap_sim_pseudonym *p =
                        eap_sim_db_get_pseudonym(data, identity, identity_len);
                return p ? 0 : -1;
        }

        if (identity[0] == EAP_SIM_REAUTH_ID_PREFIX ||
            identity[0] == EAP_AKA_REAUTH_ID_PREFIX) {
                struct eap_sim_reauth *r =
                        eap_sim_db_get_reauth(data, identity, identity_len);
                return r ? 0 : -1;
        }

        if (identity[0] != EAP_SIM_PERMANENT_PREFIX &&
            identity[0] != EAP_AKA_PERMANENT_PREFIX) {
                /* Unknown identity prefix */
                return -1;
        }

        /* TODO: Should consider asking HLR/AuC gateway whether this permanent
         * identity is known. If it is, EAP-SIM/AKA can skip identity request.
         * In case of EAP-AKA, this would reduce number of needed round-trips.
         * Ideally, this would be done with one wait, i.e., just request
         * authentication data and store it for the next use. This would then
         * need to use similar pending-request functionality as the normal
         * request for authentication data at later phase.
         */
        return -1;
}


static char * eap_sim_db_get_next(struct eap_sim_db_data *data, char prefix)
{
        char *id, *pos, *end;
        u8 buf[10];

        if (os_get_random(buf, sizeof(buf)))
                return NULL;
        id = os_malloc(sizeof(buf) * 2 + 2);
        if (id == NULL)
                return NULL;

        pos = id;
        end = id + sizeof(buf) * 2 + 2;
        *pos++ = prefix;
        pos += wpa_snprintf_hex(pos, end - pos, buf, sizeof(buf));
        
        return id;
}


/**
 * eap_sim_db_get_next_pseudonym - EAP-SIM DB: Get next pseudonym
 * @priv: Private data pointer from eap_sim_db_init()
 * @aka: Using EAP-AKA instead of EAP-SIM
 * Returns: Next pseudonym (allocated string) or %NULL on failure
 *
 * This function is used to generate a pseudonym for EAP-SIM. The returned
 * pseudonym is not added to database at this point; it will need to be added
 * with eap_sim_db_add_pseudonym() once the authentication has been completed
 * successfully. Caller is responsible for freeing the returned buffer.
 */
char * eap_sim_db_get_next_pseudonym(void *priv, int aka)
{
        struct eap_sim_db_data *data = priv;
        return eap_sim_db_get_next(data, aka ? EAP_AKA_PSEUDONYM_PREFIX :
                                   EAP_SIM_PSEUDONYM_PREFIX);
}


/**
 * eap_sim_db_get_next_reauth_id - EAP-SIM DB: Get next reauth_id
 * @priv: Private data pointer from eap_sim_db_init()
 * @aka: Using EAP-AKA instead of EAP-SIM
 * Returns: Next reauth_id (allocated string) or %NULL on failure
 *
 * This function is used to generate a fast re-authentication identity for
 * EAP-SIM. The returned reauth_id is not added to database at this point; it
 * will need to be added with eap_sim_db_add_reauth() once the authentication
 * has been completed successfully. Caller is responsible for freeing the
 * returned buffer.
 */
char * eap_sim_db_get_next_reauth_id(void *priv, int aka)
{
        struct eap_sim_db_data *data = priv;
        return eap_sim_db_get_next(data, aka ? EAP_AKA_REAUTH_ID_PREFIX :
                                   EAP_SIM_REAUTH_ID_PREFIX);
}


/**
 * eap_sim_db_add_pseudonym - EAP-SIM DB: Add new pseudonym
 * @priv: Private data pointer from eap_sim_db_init()
 * @identity: Identity of the user (may be permanent identity or pseudonym)
 * @identity_len: Length of identity
 * @pseudonym: Pseudonym for this user. This needs to be an allocated buffer,
 * e.g., return value from eap_sim_db_get_next_pseudonym(). Caller must not
 * free it.
 * Returns: 0 on success, -1 on failure
 *
 * This function adds a new pseudonym for EAP-SIM user. EAP-SIM DB is
 * responsible of freeing pseudonym buffer once it is not needed anymore.
 */
int eap_sim_db_add_pseudonym(void *priv, const u8 *identity,
                             size_t identity_len, char *pseudonym)
{
        struct eap_sim_db_data *data = priv;
        struct eap_sim_pseudonym *p;
        wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: Add pseudonym for identity",
                          identity, identity_len);
        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Pseudonym: %s", pseudonym);

        /* TODO: could store last two pseudonyms */
        p = eap_sim_db_get_pseudonym(data, identity, identity_len);
        if (p == NULL)
                p = eap_sim_db_get_pseudonym_id(data, identity, identity_len);

        if (p) {
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: Replacing previous "
                           "pseudonym: %s", p->pseudonym);
                os_free(p->pseudonym);
                p->pseudonym = pseudonym;
                return 0;
        }

        p = os_zalloc(sizeof(*p));
        if (p == NULL) {
                os_free(pseudonym);
                return -1;
        }

        p->next = data->pseudonyms;
        p->identity = os_malloc(identity_len);
        if (p->identity == NULL) {
                os_free(p);
                os_free(pseudonym);
                return -1;
        }
        os_memcpy(p->identity, identity, identity_len);
        p->identity_len = identity_len;
        p->pseudonym = pseudonym;
        data->pseudonyms = p;

        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Added new pseudonym entry");
        return 0;
}


static struct eap_sim_reauth *
eap_sim_db_add_reauth_data(struct eap_sim_db_data *data, const u8 *identity,
                           size_t identity_len, char *reauth_id, u16 counter)
{
        struct eap_sim_reauth *r;

        wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: Add reauth_id for identity",
                          identity, identity_len);
        wpa_printf(MSG_DEBUG, "EAP-SIM DB: reauth_id: %s", reauth_id);

        r = eap_sim_db_get_reauth(data, identity, identity_len);
        if (r == NULL)
                r = eap_sim_db_get_reauth_id(data, identity, identity_len);

        if (r) {
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: Replacing previous "
                           "reauth_id: %s", r->reauth_id);
                os_free(r->reauth_id);
                r->reauth_id = reauth_id;
        } else {
                r = os_zalloc(sizeof(*r));
                if (r == NULL) {
                        os_free(reauth_id);
                        return NULL;
                }

                r->next = data->reauths;
                r->identity = os_malloc(identity_len);
                if (r->identity == NULL) {
                        os_free(r);
                        os_free(reauth_id);
                        return NULL;
                }
                os_memcpy(r->identity, identity, identity_len);
                r->identity_len = identity_len;
                r->reauth_id = reauth_id;
                data->reauths = r;
                wpa_printf(MSG_DEBUG, "EAP-SIM DB: Added new reauth entry");
        }

        r->counter = counter;

        return r;
}


/**
 * eap_sim_db_add_reauth - EAP-SIM DB: Add new re-authentication entry
 * @priv: Private data pointer from eap_sim_db_init()
 * @identity: Identity of the user (may be permanent identity or pseudonym)
 * @identity_len: Length of identity
 * @reauth_id: reauth_id for this user. This needs to be an allocated buffer,
 * e.g., return value from eap_sim_db_get_next_reauth_id(). Caller must not
 * free it.
 * @counter: AT_COUNTER value for fast re-authentication
 * @mk: 16-byte MK from the previous full authentication or %NULL
 * Returns: 0 on success, -1 on failure
 *
 * This function adds a new re-authentication entry for an EAP-SIM user.
 * EAP-SIM DB is responsible of freeing reauth_id buffer once it is not needed
 * anymore.
 */
int eap_sim_db_add_reauth(void *priv, const u8 *identity,
                          size_t identity_len, char *reauth_id, u16 counter,
                          const u8 *mk)
{
        struct eap_sim_db_data *data = priv;
        struct eap_sim_reauth *r;

        r = eap_sim_db_add_reauth_data(data, identity, identity_len, reauth_id,
                                       counter);
        if (r == NULL)
                return -1;

        os_memcpy(r->mk, mk, EAP_SIM_MK_LEN);
        r->aka_prime = 0;

        return 0;
}


#ifdef EAP_AKA_PRIME
/**
 * eap_sim_db_add_reauth_prime - EAP-AKA' DB: Add new re-authentication entry
 * @priv: Private data pointer from eap_sim_db_init()
 * @identity: Identity of the user (may be permanent identity or pseudonym)
 * @identity_len: Length of identity
 * @reauth_id: reauth_id for this user. This needs to be an allocated buffer,
 * e.g., return value from eap_sim_db_get_next_reauth_id(). Caller must not
 * free it.
 * @counter: AT_COUNTER value for fast re-authentication
 * @k_encr: K_encr from the previous full authentication
 * @k_aut: K_aut from the previous full authentication
 * @k_re: 32-byte K_re from the previous full authentication
 * Returns: 0 on success, -1 on failure
 *
 * This function adds a new re-authentication entry for an EAP-AKA' user.
 * EAP-SIM DB is responsible of freeing reauth_id buffer once it is not needed
 * anymore.
 */
int eap_sim_db_add_reauth_prime(void *priv, const u8 *identity,
                                size_t identity_len, char *reauth_id,
                                u16 counter, const u8 *k_encr, const u8 *k_aut,
                                const u8 *k_re)
{
        struct eap_sim_db_data *data = priv;
        struct eap_sim_reauth *r;

        r = eap_sim_db_add_reauth_data(data, identity, identity_len, reauth_id,
                                       counter);
        if (r == NULL)
                return -1;

        r->aka_prime = 1;
        os_memcpy(r->k_encr, k_encr, EAP_SIM_K_ENCR_LEN);
        os_memcpy(r->k_aut, k_aut, EAP_AKA_PRIME_K_AUT_LEN);
        os_memcpy(r->k_re, k_re, EAP_AKA_PRIME_K_RE_LEN);

        return 0;
}
#endif /* EAP_AKA_PRIME */


/**
 * eap_sim_db_get_permanent - EAP-SIM DB: Get permanent identity
 * @priv: Private data pointer from eap_sim_db_init()
 * @identity: Identity of the user (may be permanent identity or pseudonym)
 * @identity_len: Length of identity
 * @len: Buffer for length of the returned permanent identity
 * Returns: Pointer to the permanent identity, or %NULL if not found
 */
const u8 * eap_sim_db_get_permanent(void *priv, const u8 *identity,
                                    size_t identity_len, size_t *len)
{
        struct eap_sim_db_data *data = priv;
        struct eap_sim_pseudonym *p;

        if (identity == NULL)
                return NULL;

        p = eap_sim_db_get_pseudonym(data, identity, identity_len);
        if (p == NULL)
                p = eap_sim_db_get_pseudonym_id(data, identity, identity_len);
        if (p == NULL)
                return NULL;

        *len = p->identity_len;
        return p->identity;
}


/**
 * eap_sim_db_get_reauth_entry - EAP-SIM DB: Get re-authentication entry
 * @priv: Private data pointer from eap_sim_db_init()
 * @identity: Identity of the user (may be permanent identity, pseudonym, or
 * reauth_id)
 * @identity_len: Length of identity
 * Returns: Pointer to the re-auth entry, or %NULL if not found
 */
struct eap_sim_reauth *
eap_sim_db_get_reauth_entry(void *priv, const u8 *identity,
                            size_t identity_len)
{
        struct eap_sim_db_data *data = priv;
        struct eap_sim_reauth *r;

        if (identity == NULL)
                return NULL;
        r = eap_sim_db_get_reauth(data, identity, identity_len);
        if (r == NULL)
                r = eap_sim_db_get_reauth_id(data, identity, identity_len);
        return r;
}


/**
 * eap_sim_db_remove_reauth - EAP-SIM DB: Remove re-authentication entry
 * @priv: Private data pointer from eap_sim_db_init()
 * @reauth: Pointer to re-authentication entry from
 * eap_sim_db_get_reauth_entry()
 */
void eap_sim_db_remove_reauth(void *priv, struct eap_sim_reauth *reauth)
{
        struct eap_sim_db_data *data = priv;
        struct eap_sim_reauth *r, *prev = NULL;
        r = data->reauths;
        while (r) {
                if (r == reauth) {
                        if (prev)
                                prev->next = r->next;
                        else
                                data->reauths = r->next;
                        eap_sim_db_free_reauth(r);
                        return;
                }
                prev = r;
                r = r->next;
        }
}


/**
 * eap_sim_db_get_aka_auth - Get AKA authentication values
 * @priv: Private data pointer from eap_sim_db_init()
 * @identity: User name identity
 * @identity_len: Length of identity in bytes
 * @_rand: Buffer for RAND value
 * @autn: Buffer for AUTN value
 * @ik: Buffer for IK value
 * @ck: Buffer for CK value
 * @res: Buffer for RES value
 * @res_len: Buffer for RES length
 * @cb_session_ctx: Session callback context for get_complete_cb()
 * Returns: 0 on success, -1 (EAP_SIM_DB_FAILURE) on error (e.g., user not
 * found), or -2 (EAP_SIM_DB_PENDING) if results are not yet available. In this
 * case, the callback function registered with eap_sim_db_init() will be
 * called once the results become available.
 *
 * In most cases, the user name is '0' | IMSI, i.e., 0 followed by the IMSI in
 * ASCII format.
 *
 * When using an external server for AKA authentication, this function can
 * always start a request and return EAP_SIM_DB_PENDING immediately if
 * authentication triplets are not available. Once the authentication data are
 * received, callback function registered with eap_sim_db_init() is called to
 * notify EAP state machine to reprocess the message. This
 * eap_sim_db_get_aka_auth() function will then be called again and the newly
 * received triplets will then be given to the caller.
 */
int eap_sim_db_get_aka_auth(void *priv, const u8 *identity,
                            size_t identity_len, u8 *_rand, u8 *autn, u8 *ik,
                            u8 *ck, u8 *res, size_t *res_len,
                            void *cb_session_ctx)
{
        struct eap_sim_db_data *data = priv;
        struct eap_sim_db_pending *entry;
        int len;
        size_t i;
        char msg[40];

        if (identity_len < 2 || identity == NULL ||
            identity[0] != EAP_AKA_PERMANENT_PREFIX) {
                wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: unexpected identity",
                                  identity, identity_len);
                return EAP_SIM_DB_FAILURE;
        }
        identity++;
        identity_len--;
        for (i = 0; i < identity_len; i++) {
                if (identity[i] == '@') {
                        identity_len = i;
                        break;
                }
        }
        if (identity_len + 1 > sizeof(entry->imsi)) {
                wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: unexpected identity",
                                  identity, identity_len);
                return EAP_SIM_DB_FAILURE;
        }
        wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: Get AKA auth for IMSI",
                          identity, identity_len);

        entry = eap_sim_db_get_pending(data, identity, identity_len, 1);
        if (entry) {
                if (entry->state == FAILURE) {
                        os_free(entry);
                        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Failure");
                        return EAP_SIM_DB_FAILURE;
                }

                if (entry->state == PENDING) {
                        eap_sim_db_add_pending(data, entry);
                        wpa_printf(MSG_DEBUG, "EAP-SIM DB: Pending");
                        return EAP_SIM_DB_PENDING;
                }

                wpa_printf(MSG_DEBUG, "EAP-SIM DB: Returning successfully "
                           "received authentication data");
                os_memcpy(_rand, entry->u.aka.rand, EAP_AKA_RAND_LEN);
                os_memcpy(autn, entry->u.aka.autn, EAP_AKA_AUTN_LEN);
                os_memcpy(ik, entry->u.aka.ik, EAP_AKA_IK_LEN);
                os_memcpy(ck, entry->u.aka.ck, EAP_AKA_CK_LEN);
                os_memcpy(res, entry->u.aka.res, EAP_AKA_RES_MAX_LEN);
                *res_len = entry->u.aka.res_len;
                os_free(entry);
                return 0;
        }

        if (data->sock < 0) {
                if (eap_sim_db_open_socket(data) < 0)
                        return EAP_SIM_DB_FAILURE;
        }

        len = os_snprintf(msg, sizeof(msg), "AKA-REQ-AUTH ");
        if (len < 0 || len + identity_len >= sizeof(msg))
                return EAP_SIM_DB_FAILURE;
        os_memcpy(msg + len, identity, identity_len);
        len += identity_len;

        wpa_hexdump(MSG_DEBUG, "EAP-SIM DB: requesting AKA authentication "
                    "data for IMSI", identity, identity_len);
        if (eap_sim_db_send(data, msg, len) < 0)
                return EAP_SIM_DB_FAILURE;

        entry = os_zalloc(sizeof(*entry));
        if (entry == NULL)
                return EAP_SIM_DB_FAILURE;

        os_get_time(&entry->timestamp);
        entry->aka = 1;
        os_memcpy(entry->imsi, identity, identity_len);
        entry->imsi_len = identity_len;
        entry->cb_session_ctx = cb_session_ctx;
        entry->state = PENDING;
        eap_sim_db_add_pending(data, entry);
        eap_sim_db_expire_pending(data);

        return EAP_SIM_DB_PENDING;
}


/**
 * eap_sim_db_resynchronize - Resynchronize AKA AUTN
 * @priv: Private data pointer from eap_sim_db_init()
 * @identity: User name identity
 * @identity_len: Length of identity in bytes
 * @auts: AUTS value from the peer
 * @_rand: RAND value used in the rejected message
 * Returns: 0 on success, -1 on failure
 *
 * This function is called when the peer reports synchronization failure in the
 * AUTN value by sending AUTS. The AUTS and RAND values should be sent to
 * HLR/AuC to allow it to resynchronize with the peer. After this,
 * eap_sim_db_get_aka_auth() will be called again to to fetch updated
 * RAND/AUTN values for the next challenge.
 */
int eap_sim_db_resynchronize(void *priv, const u8 *identity,
                             size_t identity_len, const u8 *auts,
                             const u8 *_rand)
{
        struct eap_sim_db_data *data = priv;
        size_t i;

        if (identity_len < 2 || identity == NULL ||
            identity[0] != EAP_AKA_PERMANENT_PREFIX) {
                wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: unexpected identity",
                                  identity, identity_len);
                return -1;
        }
        identity++;
        identity_len--;
        for (i = 0; i < identity_len; i++) {
                if (identity[i] == '@') {
                        identity_len = i;
                        break;
                }
        }
        if (identity_len > 20) {
                wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM DB: unexpected identity",
                                  identity, identity_len);
                return -1;
        }

        if (data->sock >= 0) {
                char msg[100];
                int len, ret;

                len = os_snprintf(msg, sizeof(msg), "AKA-AUTS ");
                if (len < 0 || len + identity_len >= sizeof(msg))
                        return -1;
                os_memcpy(msg + len, identity, identity_len);
                len += identity_len;

                ret = os_snprintf(msg + len, sizeof(msg) - len, " ");
                if (ret < 0 || (size_t) ret >= sizeof(msg) - len)
                        return -1;
                len += ret;
                len += wpa_snprintf_hex(msg + len, sizeof(msg) - len,
                                        auts, EAP_AKA_AUTS_LEN);
                ret = os_snprintf(msg + len, sizeof(msg) - len, " ");
                if (ret < 0 || (size_t) ret >= sizeof(msg) - len)
                        return -1;
                len += ret;
                len += wpa_snprintf_hex(msg + len, sizeof(msg) - len,
                                        _rand, EAP_AKA_RAND_LEN);
                wpa_hexdump(MSG_DEBUG, "EAP-SIM DB: reporting AKA AUTS for "
                            "IMSI", identity, identity_len);
                if (eap_sim_db_send(data, msg, len) < 0)
                        return -1;
        }

        return 0;
}
